Strip processing apparatus having air locks between tanks

ABSTRACT

In a system for plating strip fed workpieces having a plurality of liquid containing reservoirs interconnected by air-lock mechanisms, the air-lock mechanisms include conduit members connecting adjacent reservoirs to form a path of travel between the reservoirs above the normal liquid level therein. The conduit members are connected in fluid communication with a source of pressurized air and with an air chamber positioned in the base of the reservoirs, so that during the plating process, air is supplied to the air chamber to displace liquid from the base of the reservoirs and raise the liquid level in the tanks to immerse the strip fed workpieces. The pressurized air in the conduit member prevents liquid from flowing out of the respective reservoirs as the workpieces pass therethrough.

United States Patent 1151 3,687,104

Capper et a1. Aug. 29, 1972 [541 STRIP PROCESSING APTARATUS 3,350,248 10/1967 Demarest, Jr. et al ..1 18/405 HAVING AIR LOCKS BETWEEN UX TANKS Primary Examiner-Morris Kaplan [721 Inventors Harry capperklcham Attorney-William J. Keating, Ronald D. Grefe,

Wagner 0f Harrisburg Gerald K. Kita, Frederick w. Rating and Jay L. Seitchik [73] Assignee: AMPIncorporated, Harrisburg, Pa.

[22] Filed: Nov. 27, 1970 [21] Appl. No.: 93,334

[57] ABSTRACT In a system for plating strip fed workpieces having a plurality of liquid containing reservoirs interconnected by air-lock mechanisms, the air-lock mechanisms in- 52 us. 01 ..l18/405, 118/421 elude conduit members connecting adjacent reservoirs 51 Int. Cl ..B05c 3/15 to foml a P of travel between the reservoirs above [58] w of Search 118/404, 405, 421 50, 501; the normal liquid level therein. The conduit members 68/9; 1 17/DIG 6, 21; 277/235 are connected in fluid communication with a source of pressurized air and with an air chamber positioned in [56] References Cited the base of the reservoirs, so that during the plating process, air is supplied to the air chamber to displace UNITED STATES PATENTS liquid from the base of the reservoirs and raise the liquid level in the tanks to immerse the strip fed work- 3,383,906 5/1968 Gillet ..118/421 X pieces The pressurized air in the conduit member ggg g fi 3/1965 Starr "118/405 x prevents liquid from flowing out of the respective g g 1 25:1? reservoirs as the workpieces pass therethrough.

3,209,723 lO/ 1965 Schrodersecker18/404 X 13 Claims, 2 Drawing Figures This invention relates generally to belt plating systems for plating of metal parts which may be used for forming electrical connectors, and more particularly to air-lock mechanisms for connecting liquid reservoirs in the plating apparatus to permit movement of strip fed workpieces therebetween, while preventing transfer of the liquids between the respective reservoirs.

Electroplating processes have been proposed in the past in which strip fed workpieces are transported through a plurality of liquid containing reservoirs wherein each reservoir contains a different liquid utilized in the plating process. For example, the series of reservoirs may include a reservoir containing a cleaning fluid, through which the strip of workpieces is initially fed, in series with a reservoir containing a rinse liquid for removing cleaning fluid from the work pieces prior to the introduction of the workpieces to a tank containing either an electrolyte or plating metal solution which is adapted to be electrolyzed to plate the workpieces to the desired thickness.

In such electroplating processes it is desirable that the strength and purity of the electrolyte solution be maintained; thus it is required that the liquids in each of the respective tanks in the series be isolated from one another and that no seepage or spillage be permitted therebetween.

The plating operation is most rapidly achieved by a continuous process in which the work pieces are strip fed through each of the reservoirs, rather than individual dipping of workpieces within the separate solutions in a sequential operation as has been proposed in the past. Further, to avoid undue flexing of the strip fed workpieces, it is desirable that the strip be moved through the reservoirs in a straight line. In the latter case it thus becomes necessary to pass the strip fed workpieces directly through the tanks rather than into and out of the tops thereof, thereby necessitating the use of a sealing system at the sides of the reservoirs, in the path of travel of the workpieces, to prevent liquid from escaping or spilling therefrom.

Accordingly, it is an object of the present invention to facilitate the continuous strip feeding of parts between reservoirs different liquids.

A further object of the invention is to isolate liquids in adjacent interconnected reservoirs.

A still further object of the invention is to permit passage of strip fed workpieces between adjacent reservoirs containing liquids while retaining the liquids in their respective reservoirs.

In accordance with an aspect of this invention an airlock system for use in a strip fed workpiece plating apparatus having a plurality of liquid containing reservoirs is provided for interconnecting the reservoirs to permit passage of the strip fed workpieces therethrough while retaining liquid within the respective tanks. The air-lick system includes individual conduit members interconnecting adjacent reservoirs in the plating apparatus. Each of the conduit members is connected to a source of pressurized air or gas and permits the strip fed workpieces to pass from one reservoir to another while pressurized air prevents fluid in the adjoining tanks from flowing through the conduits and intermingling. Initially the liquid level in each of the reservoirs is below the point of connection of the conduit to the reservoir. An air chamber, as for example, an inflatable bag is located in the base of each tank and connected to the source of pressurized air, in conjunction with the conduit member, and when air is supplied to the conduit members, the bags inflate to raise the liquid level in the reservoirs thereby to immerse the strip fed workpieces-in the liquids as required by the plating process. A retaining member or plate is located within each of the reservoirs and the inflatable bag is positioned between the plate and the base of the reservoirs to prevent the bag from floating to the top of the liquid during the plating process.

The above, and other objects, features and advantages of this invention, will be apparent in the following detailed description of an illustrative embodiment of this invention which is to be read in connection with the accompanying drawing wherein:

FIG. 1 is a schematic sectional view of a pair of reservoirs utilized in a belt plating apparatus in which one embodiment of the present invention may be employed.

FIG. 2 is a schematic sectional view of a pair of reservoirs utilized in a belt plating apparatus in which another embodiment of the present invention may be employed.

Referring to the drawing in detail, and initially to FIG. 1 thereof, it will be seen that a portion of a plating apparatus 10, of the type in which the present invention may be employed, generally comprises a pair of reservoirs l2 and 14 through which a strip or belt 16 of workpieces 18 is moved during the plating process. Such process may typically include a number of such reservoirs, as for example in a nickel plating process wherein at least four reservoirs would be provided containing, in serial order, a cleaning liquid, a rinse liquid, a nickel plating electrolyte solution and a second rinse. Only two reservoirs l2 and 14, containing difierent liquids 20 and 22 respectively, are shown in FIG. 1, for simplicity of illustration, and it is to be understood that the connections between the remaining reservoirs in such a plating process are similar in construction to those illustrated in the drawing. It is noted that strip 16 may be a generally flat stock member adapted to be plated in a plating process. In the drawing, however, the strip is shown schematically as a performed member wherein workpieces 18 represent electrical contacts.

Reservoirs l2 and 14 are connected by an air-lock 24 which includes a conduit 26 providing a path of travel between the reservoirs for the strip 16 of workpieces l8. Conduit 26 extends into side walls 28 and 30 respectively of tanks 12 and 14, and is mounted in liquid sealing relation thereto with conventional rubber gaskets or the like (not shown). Normally, the liquid level within the reservoirs is below the point of connection 32 of conduit 26 within the walls 28 and 30, as indicated by the dotted line 34 in each of the reservoirs, so that the liquid within each of the reservoirs cannot be inadvertently comingled.

When it is desired to place the electroplating apparatus 10 into operation, it is necessary to raise the liquid level in the reservoirs to a point above the point of connection 32 of conduit 26 with the reservoirs so that the continuously fed strip 16 will be immersed within the liquids in the respective reservoirs. To this end an air chamber comprising, in this embodiment, an inflatable bag 36 is positioned within each of the tanks adjacent the base thereof. Bags 36 is adjacent tanks are connected'to a common feed conduit 38 through which pressurized air or gas may be supplied to inflate the bags and thereby displace the liquid in the reservoirs to raise the liquid level therein. Conduit 38 is mounted in walls 28 and 30 in liquid sealing relation in the same manner as conduit 26. It is noted that any suitable gas, other than air, may also be conveniently used to inflate bags 36, however, the term air as used in this description is intended to refer to all such suitable gases.

Conduit 38 is connected to conduit 26 by an intermediate conduit 40, and air is supplied to conduit 38 through conduits 26 and 4% from an inlet conduit 42 connected to conduit 2s. it is noted that conduits 26, 38, 4t and 42 are preferably formed as an integral member as illustrated schematically in the drawing. However, itis contemplated that each of these conduits may be formed as separate elements and connected in fluid communication in any conventional manner. Further, conduits 38 and 26 may be separately connected to the source of pressurized air.

Conduit 42 is adapted to be connected to the source of air by conventional fittings (not shown), in order to inflate bags 36 and raise the surface of liquids 2i) and 22 from level 34 to the full line position shown in the drawing above conduit 26. When the liquid level is thus raised, pressurized air is simultaneously present within conduit 26 and the air is supplied under sufficient pressure to form an air-lock therein which maintains liquids 2i) and 22 within their respective reservoirs 112 and 14 while permitting the strip in of workpieces 118 to pass therebetween. It is noted that conduits 26 are formed to conform generally with the cross-sectional size of the strip 16 so that the pressures required to maintain the air-lock are not too great due to air losses through the conduits.

During the plating process, a portion of the air supplied to conduit 26 will escape into the reservoirs to provide some agitation to the solution therein. This is particularly important for reservoirs containing rinse or cleaning solutions since the agitated liquid will more effectively scrub residual impurities deposited on the workpieces. The amount of air thus escaping is limited by the fact that the passages 27 therein for strip 16 conform generally to the cross-section of the strip.

To maintain bags 36 in the base portions of the reservoirs after they are inflated and to avoid interference by the bags with the transport of strip 16, a retention plate $3 is mounted within each of the reservoirs and is secured in any convenient manner to at least one of the walls thereof, as for example walls 28 and 30. Plates 43 have apertures 24 therein to insure displacement of liquid from beneath the plate as bags 36 are inflated and the liquid level is raised.

The ends of each of the tanks are provided with airlocks 46 having conduits d8 which form part of the path of travel for strip lid. Conduits 48 include inlet pipes 50 which are adapted to be connected to the source of pressurized air, in a manner similar to conduits 32. Thus conduits 48 will act in the same manner as conduits 26 to prevent escape of liquid from within their associated reservoirs during the plating process.

It is noted that where a series of reservoirs are utilized, alternate junctures between adjacent reservoirs may utilize air-locks similar to air-locks 50 since the inflatable bags within such reservoirs would be inflated by means of the air-lock systems 24 associated with the other side of each of the respective reservoirs.

When the electroplating process is completed, and all of the workpieces are satisfactorily plated, the air flow to the various air-locks is shut off and bags 36 deflate under the pressure of the liquid within the reservoirs, so that the liquid level is returned to level 34, below the point of connection of conduits or transfer tubes 26 and 48 with their respective reservoirs.

Referring now to FIG. 2, there is shown another embodiment of the present invention for use in a strip fed workpiece plating apparatus 60 similar to that described above. For brevity in describing this embodiment, like numerals have been utilized to represent parts corresponding to those described with regard to the embodiment of FIG. 1.

In this embodiment the air chambers for rasing the liquid level within reservoirs i2 and 14 are formed as relatively rigid containers 62 preferably constructed of a plastic material secured to the base of its associated reservoir. Containers 62 are generally rectangular structures somewhat smaller in area than the reservoirs themselves and each has an impermeable top wall 64, base 66, end walls 68 and side walls 70. Conduit 38 is connected in liquid sealing relation through walls 28 and 30 of reservoirs i2 and 14 to each of the containers 62, so that air supplied through conduits 42 and 38 will be supplied to the containers. Side walls 70 are pro vided with a plurality of apertures '72 adjacent base 66, and as air is supplied to the container, liquid within the container is displaced, through apertures '72, to raise the liquid level within the reservoirs and immerse strip 16 therein.

As air is continuously supplied to conduits 42 and 38 during the plating process, some air will also escape through openings 72. The discharge of liquid and air in fine bubbles from container 62 produces further agitation of the liquid within reservoirs, which, as mentioned above, is a desirable feature in the plating process.

As in the prior embodiment, air pressure within conduits 26 prevents liquid within reservoirs l2 and 14 from seeping or spilling therefrom and thus intermingling. Further, conduits as, in this and the prior embodiment, may be provided with flexible vanes 72, formed of a latex material to assist in preventing liquid from seepage. These vanes contact strip 16 and follow the contour thereof to further limit escape of air through conduit 26. The vanes act somewhat as a valve to limit loss of air therethrough, and thus less air pressure is required to prevent liquid seepage.

Upon completion of the plating process, the air supply to conduit 42 is shut off and liquid thus is permitted to return to container 62 through apertures 72, whereby the liquid level within the reservoirs is lowered below conduits 26 to the level of dotted line 34.

It is noted that while conduits 26 and 38 have been illustrated as integral members joined by conduit 40, it is contemplated that these members may be independent of each other and may be separately connected to the source of air pressure. Further, it is also contemplated that the air supply to containers 62 may be introduced through a conduit extending through the top 64 thereof to insure that substantially all of the liquid within container 52 is discharged therefrom during the plating process.

The invention presents several significant advantages which cannot be obtained with prior art electroplating systems. One significant advantage is that the plating line can be relatively short as compared with a conventional in and out plating line having pulleys to guide the strip vertically from, and into, the tanks. As a result, a system in accordance with the invention occupies substantially less floor space than other systems. The limited length of the plating line, and the short distance between successive tanks, is also advantageous in that there is less opportunity for passivation of the strip as it travels through a gaseous atmosphere between the tanks. Such passivation, or any other chemical effect induced between tanks, can seriously effect the quality of the finished plating.

It will be noted that the disclosed system for maintaining pressurization is a fail-safe system in that in the event of loss of air pressure, the level of the liquid in the tanks would fall simultaneously with loss of the air seal between tanks so that the liquids in adjacent tanks would not be mixed. Furthermore it should be noted that the tanks can be covered as indicated in the drawing thereby to prevent contamination of the liquids in the tanks by dust or other foreign particles which could seriously effect plating. Finally, an advantage is achieved in that the continuous passage of air through the tanks agitates the liquid in the tanks and thereby assures continuous mixing of the liquids.

The principles of the invention can be used for plating a wide variety of metals on a wide variety of types of metal strip. As mentioned above, the invention can be used in a continuous belt plating apparatus but it can also be used with conventional plating arrangements and is not limited to belt plating systems.

Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawing, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of this invention.

What is claimed is:

l. An air-lock mechanism adapted to be connected to a source of pressurized air for use in a belt plating apparatus having liquid containing reservoirs comprising, first conduit means interconnecting said reservoirs above the normal level of liquid therein and defining therebetween a path of travel for said belt, second conduit means in fluid communication with said first conduit means and connected to said reservoirs, and an air chamber positioned in each of said reservoirs in communication with said second conduit means whereby air supplied to said conduits from said source enters said air chambers to displace said liquid and raise the liquid level in said reservoirs above said first conduit means to immerse said belt, the pressurized air in said first conduit means retaining liquid within the respective reservoirs as said belt passes therethrough.

2. An air-lock mechanism as in claim 1 wherein said air chamber comprises an inflatable bag.

3. An air-lock mechanism as in claim 2 including means in said reservoirs for maintaining said inflatable bags adjacent the has thereof.

. An air-lock mec amsm as m claim 3 wherein said therebetween for said workpieces, said air-lock mechanism being adapted to be connected to a source of pressurized air and comprising, conduit means for connecting adjacent reservoirs above the normal liquid level therein, means in each reservoir for raising said liquid level, and means for connecting said conduit means and said liquid level raising means to said source of pressurized air, whereby said liquid level is raised above said conduit means to immerse said strip fed workpieces and pressurized air in said conduit means retains liquid within the respective reservoirs as said workpieces pass therethrough.

7. An air-lock mechanism as in claim 6 wherein said means for raising the liquid levels in said reservoirs comprises an individual inflatable bag in each of said reservoirs, said bags being in fluid communication with said conduit means for inflation by said pressurized air to raise said liquid levels.

8. An air-lock mechanism as in claim 7 including means in said reservoirs for maintaining said inflatable bags adjacent the base thereof. I

9. An air-lock mechanism as in claim 8 wherein said maintaining means comprises a perforated plate secured to at least one wall of its associated reservoir and in spaced relation to the base thereof.

10. An air-lock mechanism as in claim 7 including second conduit means interconnecting the inflatable bags in adjacent reservoirs, said second conduit means being in fluid communication with the first mentioned conduit means for simultaneously distributing air to said bags.

11. An air-lock mechanism as in claim 6 including flexible vane members in said conduit means adapted to engage said workpieces and form a partial air seal therewith to impede discharge of air from said conduits to said reservoir.

12. An air-lock mechanism as in claim 6 wherein said means for raising the liquid levels in said reservoir comprises a perforated container in each of said reservoirs said containers being in fluid communication with said conduit means whereby liquid within said containers is displaced therefrom by said pressurized air to raise said liquid levels.

13. An air-lock mechanism as in claim 12 wherein said containers are secured to the base of their associated reservoirs. 

1. An air-lock mechanism adapted to be connected to a source of pressurized air for use in a belt plating apparatus having liquid containing reservoirs comprising, first conduit means interconnecting said reservoirs above the normal level of liquid therein and defining therebetween a path of travel for said belt, second conduit means in fluid communication with said first conduit means and connected to said reservoirs, and an air chamber positioned in each of said reservoirs in communication with said second conduit means whereby air supplied to said conduits from said source enters said air chambers to displace said liquid and raise the liquid level in said reservoirs above said first conduit means to immerse said belt, the pressurized air in said first conduit means retaining liquid within the respective reservoirs as said belt passes therethrough.
 2. An air-lock mechanism as in claim 1 wherein said air chamber comprises an inflatable bag.
 3. An air-lock mechanism as in claim 2 including means in said reservoirs for maintaining said inflatable bags adjacent the base thereof.
 4. An air-lock mechanism as in claim 3 wherein said maintaining means comprises a perforated plate secured to at least one wall of its associated reservoir, in spaced relation to the base thereof.
 5. An air-lock mechanism as in claim 1 wherein said air chamber comprises a perforated container mounted in said reservoir.
 6. In a system having liquid containing reservoirs for plating strip fed workpieces and an air-lock mechanism connecting said reservoirs and forming a path of travel therebetween for said workpieces, said air-lock mechanism being adapted to be connected to a source of pressurized air and comprising, conduit means for connecting adjacent reservoirs above the normal liquid level therein, means in each reservoir for raising said liquid level, and means for connecting said conduit means and said liquid level raising means to said source of pressurized air, whereby said liquid level is raised above said conduit means to immerse said strip fed workpieces and pressurized air in said conduit means retains liquid within the respective reservoirs as said workpieces pass therethrough.
 7. An air-lock mechanism as in claim 6 wherein said means for raising the liquid levels in said reservoirs comprises an individual inflatable bag in each of said resErvoirs, said bags being in fluid communication with said conduit means for inflation by said pressurized air to raise said liquid levels.
 8. An air-lock mechanism as in claim 7 including means in said reservoirs for maintaining said inflatable bags adjacent the base thereof.
 9. An air-lock mechanism as in claim 8 wherein said maintaining means comprises a perforated plate secured to at least one wall of its associated reservoir and in spaced relation to the base thereof.
 10. An air-lock mechanism as in claim 7 including second conduit means interconnecting the inflatable bags in adjacent reservoirs, said second conduit means being in fluid communication with the first mentioned conduit means for simultaneously distributing air to said bags.
 11. An air-lock mechanism as in claim 6 including flexible vane members in said conduit means adapted to engage said workpieces and form a partial air seal therewith to impede discharge of air from said conduits to said reservoir.
 12. An air-lock mechanism as in claim 6 wherein said means for raising the liquid levels in said reservoir comprises a perforated container in each of said reservoirs said containers being in fluid communication with said conduit means whereby liquid within said containers is displaced therefrom by said pressurized air to raise said liquid levels.
 13. An air-lock mechanism as in claim 12 wherein said containers are secured to the base of their associated reservoirs. 